1. Field of the Invention
The present invention relates to a method of fabricating a display panel having a luminous portion which emits light concentrated in the viewing direction, and particularly to a lens disposed on the front of the front panel.
2. Description of the Related Art
Conventionally, there are various display devices such as CRTs and plasma displays. For such display devices, there is a strong demand to increase brightness as much as possible. In the self-luminous-type display devices such as CRTs and plasma displays, the produced light is emitted with no directivity and relatively diverges in the viewing direction. This type of display device has the advantage of a wide angle of view. However, most of the emitted light diverges in other directions, not to a user which is on the front of the display panel, and the brightness efficiency is poor.
In order to improve the poor brightness efficiency, a display panel has been proposed wherein micro lens groups are disposed on the front surface to condense the diverged light towards the front. This structure enables the brightness of the display panel to be improved, even when the same amount of light is emitted.
A typical CRT or plasma display has a glass front panel. Lenses can theoretically be formed on the top surface of the front panel, but it is in practice very difficult to form lenses on the top surface of the CRT. Lenses can be formed on the glass display panel but may be deformed in the sealing and sintered process to seal the inner space of the display panel structure. In either case, one-piece molding lenses with the display panel makes the front panel quite expensive.
One practical method is made by the steps of fabricating a lens panel with a heat-resistant transparent material such as glass or polycarbonate and then bonding the lens panel to the front surface of the front panel with an adhesive agent. However, this method has a serious disadvantage in that the display panel becomes heavier because of the attached member and that a long distance between the lens and the luminous position decreases the light-condensing angle, thus narrowing the angle of view. A one-piece molding technique is disclosed, for example, in Japanese Patent Laid-open Publication No. Hei 2-267842(Nov. 11, 1990).